The day is fast approaching when scientists will finally be able to reconstruct a person's heart from a clump of cells and a simple scaffold. We're not there yet, but this video will show you how it's done.

As Maher notes, the heart is the third most needed organ after the kidney and the liver, but it has a much tougher job. It needs to beat constantly — and without a back-up — to pump some 7,000 litres of blood each day. Its complex structure is comprised of various chambers and valves, each of them built upon several different types of specialized muscle cells called cardiomyocytes.

Image: Nature News/Nik Spencer.

Needless to say, bioengineering a fully functional and reliable heart will not be easy. But the process will follow three basic steps: (1) creating a protein scaffold by removing all cells from a donated heart, (2) seeding the scaffold with endothelial precursor cells and influencing their growth, and (3) getting the heart to beat.